Cayenne may increase the risk of bleeding or potentiate the effects of warfarin therapy.

– Am J Health Syst Pharm 2000 Jul 1;57(13):1221-7; quiz 1228-30 —
Potential interactions between alternative therapies and warfarin. — Heck AM, DeWitt BA, Lukes AL. — School of Pharmacy and Pharmacal Sciences, Purdue University, Indianapolis, IN, USA.

Loss of enamel and a deep black stain of the teeth in a 40-year-old diabetic patient are strongly suggested to be caused by the daily consumption of a cheap white wine and, possibly, by the chewing of cayenne. The wine proved to be rather acid, thereby promoting abrasion as a result of gnashing, and to contain a high concentration of tannin.

– Oral Surg Oral Med Oral Pathol 1987 Oct;64(4):427-31 — An unusual case of black teeth. — Schuurs AH, Abraham-Inpijn L, van Straalen JP, Sastrowijoto SH.

Around one third of patients experienced local adverse events with capsaicin as a topical treatment for pain.

– BMJ. 2004 Apr 24;328(7446):991. Epub 2004 Mar 19. — Systematic review of topical capsaicin for the treatment of chronic pain. — Mason L, Moore RA, Derry S, Edwards JE, McQuay HJ.

Cayenne was responsible for skin reactions.

-Allergy 1981 Oct;36(7):487-93 — Immediate skin test reactions to spices. — Niinimaki A, Hannuksela M.

Cayenne can increase the amount of absorption rate of other herbs and prescription medications due to its’ heating properties.

Results show that Capsicum ingestion reduces oral drug bioavailability, likely as a result of the gastrointestinal effects of capsaicin.

– Can J Physiol Pharmacol 1999 Jun;77(6):441-6 — Ingestion of chilli pepper (Capsicum annuum) reduces salicylate bioavailability after oral asprin administration in the rat. — Cruz L, Castaneda-Hernandez G, Navarrete A.

Inhibitory effect of capsaicin on intestinal glucose absorption in vitro.

– Food Cosmet Toxicol 1978 Oct;16(5):469-73 — Inhibitory effect of capsaicin on intestinal glucose absorption in vitro. — Monsereenusorn Y, Glinsukon T.

It was found that a single dose of Capsicum fruit could affect pharmacokinetic parameters of theophylline, while a repeated dose affected the metabolic pathway of xanthine oxidase.

– Eur J Drug Metab Pharmacokinet 1995 Jul-Sep;20(3):173-8 — Theophylline pharmacokinetics and metabolism in rabbits following single and repeated administration of Capsicum fruit. — Bouraoui A, Brazier JL, Zouaghi H, Rousseau M.

Use extreme caution around children when using cayenne and capsaicin products. Recommendations have been found on the internet to use cayenne as a deterrent to thumb sucking — please do not follow those questionable instructions.